The present invention relates to medical apparatus, particularly to a medical implement and a kit including such an implement, and also to a method, for attaching a suture to a bone. The invention is especially useful in an arthroscopic surgical procedure for attaching a tendon of a rotator cuff muscle to the humerus bone for repairing a damaged shoulder joint, and is therefore described below with respect to such a procedure.
While the shoulder joint has a great range of motion, it is not very stable. Four rotator cuff muscles (supraspinatus, infraspinatus, subscapularis and teres minor) surround the shoulder joint and provide the power to lift and rotate the arm while keeping the head of the upper arm bone (humerus) in approximation to the socket in the shoulder blade (glenoid) for stability. Each of these muscles is attached by a tendon to the humerus bone. The supraspinatus muscle is attached by the supraspinatus tendon to the superior aspect of the greater tubercle. The infraspinatus muscle is attached by the infraspinatus tendon to the posterolateral aspect of the greater tubercle. The teres minor muscle is attached by the teres minor tendon to the lower aspect of the greater tubercle. The subscapularis muscle is attached by the subscapularis tendon to the lesser tubercle. As one ages, these muscles and tendons become thinner and prone to rupture. A rotator cuff tear may develop gradually or may result suddenly from a single traumatic event. In a younger patient, rupture is usually associated with significant trauma. Rotator cuff tears are tears of one or more of the four tendons of the rotator cuff muscles listed above. Tears of the surpraspinatus tendon are the most common, most often involving detachment of the tendon from the bone. The tear of the supraspinatus tendon usually occurs at its point of insertion onto the humeral head at the greater tubercle. Since this tear is the most common, the following description will refer to the supraspinatus tear. However, it is submitted that the invention described below is applicable to any of the rotator cuff tears and in fact to any tear of a tendon from a bone.
When surgical intervention is indicated to repair a rotator cuff tear, the procedure can be performed as an open surgical procedure, or as a minimally invasive (arthroscopic) surgical procedure. Both procedures aim to re-attach the tendon to the bone over an area extending from the anatomical neck to the lateral surface of the tubercle. The relatively large area of attachment is desirable for strengthening purposes and for assisting recovery and healing. This procedure of osseointegration of the tendon to the bone causes bony tissue to be formed around the tendon and anchors it in place.
In open surgery, after the joint has been exposed, the tubercle is accessed laterally, and a row of holes are drilled aiming to exit in the area of the anatomical neck. Sutures are led through these holes; the tendon is stretched to lie over the planned area of attachment; and the suture coming from the exit point is passed through the tendon. When the sutures leading from the inlet and exit points are knotted, one strand overlies the tendon, thus achieving attachment over the surface of the tubercle from the lateral inlets to the anatomical neck.
In contrast, the arthroscopic procedures use bone anchors. Two rows of anchors are implanted, one in the neck area and one on the lateral surface of the tubercle. Sutures leading from the anchors are passed through the tendon and are knotted over it.
Both procedures have shortcomings. With the open method, the bone tunnels for the sutures can be drilled only in one direction, from the lateral upwardly to the anatomical neck. Access for drilling from the anatomical neck at an angle to reach the side of the tubercle is obstructed by the patient's neck and head. It is difficult to achieve exactly the desired exit points for the drill. Exiting on the spherical humeral head must be avoided. Drilling at a more acute angle for safety may result in being too close to the surface of the tubercle.
A minimally invasive (arthroscopic) method is desirable when not contra-indicated from medical considerations. However, the conventional arthroscopic procedure uses anchors resulting in points or lines of attachment, rather than in attachments over a significant surface.